As a technique capable of measuring a visual line with high accuracy in a non-contact manner, a corneal reflection method has been known.
This method uses reflected light on an eyeball, and therefore the accuracy is largely affected by an individual variation of an eyeball shape. Accordingly, a measured visual line is corrected by using an error belonging to a person.
PTL 1 discloses a gaze point detection device including a plurality of stereo cameras for obtaining facial images of an object person, a light source disposed outside an opening of each of the stereo cameras, a control circuit, and an image processing device.
The image processing device calculates an angle of a visual line of the object person by using a function based on the facial images, calculates a direction of the visual line while correcting the function such that directions of visual lines calculated corresponding to the plurality of stereo cameras are close to each other, and detects a gaze point of the object person on a display screen.